Question Hard Disk HPA and DCO

[s-e-b-a]

Do all hard disks have HPA and DCO?

If not, does it depend on the kind of disk or does it depend on the manufacturer?

 

[fzabkar]

The DCO command set (B1h) has been made obsolete.

Here is an SSD that supports these commands (page8):
https://www.kingston.com/datasheets/SVP100ES2_us.pdf

Page 622 of the following standards document states that command B1h is obsolete.

http://www.t13.org/Documents/UploadedDocuments/docs2016/di529r14-ATAATAPI_Command_Set_-_4.pdf

The same document also states that command F9h (SET MAX ADDRESS) is now obsolete. That's the command that sets the size of the HPA.

That said, often you will find that HDD manufacturers retain some of the legacy commands for compatibility reasons. For example, the command for reading SMART attribute thresholds has been obsolete for quite some time, but no manufacturer has yet removed it, AFAIK.